1. Field of the Invention
The present invention is directed to a method and apparatus which permit each processor card of a modular multi-processor card system to communicate with other processor cards including a supervisor module processor card.
2. The Background Art
Modular multi-processor systems are known in the art. Such systems typically include a back plane having a number of receptacles to which processor cards can be attached. It is often necessary or desirable to establish communications among the various processor cards for various reasons. In the past, such communications were sometimes implemented over parallel bus type architectures using large numbers of conductors to pass communications among the processor cards. Such systems, while fit for their intended purposes, have the drawback that they utilize more conductors than necessary to carry out the needed communications. They also require custom drivers and protocols which adversely impact development time, cost, design architecture, debugging and troubleshooting. Such systems are often complex and utilize valuable resources such as the conductors. Other systems have implemented such communications using several separate serial channels based upon RS232 UART devices. This approach resulted in fewer conductors used in the backplane, but the drawback was that the communications speed was limited by the serial performance of the UARTs. It should also be noted that almost all prior implementations of such interprocessor communications systems required centralized arbitration which means that a master had to be present in the system. Failure of a master causes whole communications channels to be shut down.
Accordingly, it would be desirable to provide an improved method and apparatus for carrying out interprocessor communications while utilizing fewer conductors, higher bandwidth and standard drivers and protocols, thus reducing costs, development time and effort and/or freeing up additional conductor paths for other purposes.